Compositions and methods for detecting and killing termites

ABSTRACT

Significant concentrations of naphthalene were detected in carton nests of Formosan subterranean termites, Coptotermes formosanus Shiraki, collected from Florida, Hawaii, and Louisiana. This is the first report of naphthalene being associated with termites or any other insects. Naphthalene and other compounds associated with termite carton nests may be used to increase termite bait acceptance. New attractant molecules include 2-phenoxyethanol. New feeding stimulants include ergosterol. A list of volatile compounds associated with termite nests is presented, compounds that may be used to detect termite nests.

This is the United States national stage of international applicationPCT/US98/25989, international filing date Dec. 8, 1998; and is also adivisional of national application Ser. No. 08/988,911, filed Dec. 11,1997, now U.S. Pat. No. 5,874,097.

TECHNICAL FIELD

This invention pertains to compositions and methods for detecting andkilling termites.

BACKGROUND ART

The Formosan subterranean termite, Coptotermes formosanus Shiraki, is amajor worldwide pest that attacks both living trees and structural wood.Unlike other subterranean termites, the Formosan termite can establish acolony that does not touch the ground.

Coptotermes formosanus is native to southeast Asia, but is now alsofound in Hawaii, along the southeastern Atlantic coast of the UnitedStates, and in the Gulf South of the United States. First discovered inthe United States in 1965, C. formosanus has gradually expanded itsgeographic domain. The largest single locus of C. formosanus in theUnited States is in south Louisiana, with heavy infestations in LakeCharles and New Orleans. C. formosanus may in some cases displace nativeReticulitermes spp.

C. formosanus continues to cause great structural damage to manybuildings in the Lake Charles and New Orleans areas, including damage tomany buildings of historic significance. There is particular concern forthe future of New Orleans' French Quarter, where many historic buildingsare already severely damaged and would be quite expensive to repair.

Three principal methods have been used in the past to controlCoptotermes: (1) chemical and physical barriers to prevent termites fromattacking wood, (2) wood preservatives and termiticides used to protectinfested or susceptible wood, and (3) destruction of a termite colony byexcavation of the nest.

Chemical barriers and termiticides have generated public concern overenvironmental safety.

In China excavation of the nest has been one of the main methods used tocontrol Formosan termites. However, locating a termite nest is typicallyvery time-consuming, limiting the usefulness of the practice.

Using a bait to deliver a termiticide has several advantages. Baitstypically require only a small amount of the toxicant, and they targetonly the insects that feed on the bait (or are re-fed the bait by nestmates). Thus non-target organisms are not affected, diminishing theenvironmental impact of the toxicants. Use of a bait can make itunnecessary to locate the nest, because many termites, includingFormosan termites, engage in trophallaxis (transfer of food to othercolony members). Thus the toxicant may be spread throughout a colonyafter feeding by only a few foraging termites. Bait methods havepreviously been used to detect and experimentally control subterraneantermites, and to trap termites for studies on termite ecology.

A major problem with existing baiting techniques against Coptotermesspecies has been inconsistent bait acceptance. Baits placed withintermite galleries are often bypassed and left uneaten. The use oftermite baits is different from the use of ant baits and cockroachbaits, because it is usually not possible to remove competing foodsources for termites. Attractants and feeding stimulants have sometimesincreased the consistency of bait acceptance, but there remains acontinuing need for improved termite baits.

There is a continuing need for improved techniques for killing termites.There is also a continuing need for improved methods for detectingtermite nests. Current detection techniques rely primarily on visualinspection. Unfortunately, termite nests are frequently overlooked byvisual inspection techniques. Formosan termite nests, in particular, canoften be outwardly invisible for years, while the termites causeconsiderable unseen damage.

C. formosanus uses soil, masticated wood, and excrement, cemented bysaliva and excrement, to make its nests, termed “cartons.” Gallery andshelter tube systems connect primary nests to accessory nests andfeeding sites. C. formosanus colonies continually expand their foragingareas by enlarging the nest, or by building accessory nests.

J. Chen et al., “Naphthalene in Formosan Subterranean Termites and TheirNest Carton,” Poster Presentation, 213th American Chemical SocietyNational Meeting (San Francisco, Calif., April 1997) presented some ofthe results disclosed in the present specification.

U.S. Pat. No. 5,637,298 discloses that 2-naphthalenemethanol and certainderivatives of 2-naphthalenemethanol are termite attractants, and thatthese attractants may be used to increase bait acceptance by termites.

G. Henderson, “No Fungus Among Us,” PCT Pest Control Technology, pp.60-61 (May 1997) states that four unidentified chemicals used byFormosan termites to inhibit fungal growth had been identified, and thatthe chemicals were toxic to ants.

Both the introduced Formosan subterranean termite, Coptotermesformosanus Shiraki, and subterranean termites in the genusReticulitermes exhibit trail-following behaviors. M. Tokoro et al.,“Isolation and primary structure of trail pheromone of the termite,Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae),” Wood Res.,vol. 76, pp. 29-38 (1989) reported isolation of the trail pheromone fromC. formosanus, and identified it as (Z,Z,E)-3,6,8-dodecatrien-1-ol(DTE-OH), which has also been reported to be the trail-followingpheromone of R. virginicus (Banks) and R. santonensis (Feytaud). See F.Matsumura et al., “Isolation and Identification of TermiteTrail-Following Pheromone,” Nature, vol. 219, pp. 963-964 (1968); and N.Laduguie et al., “Isolation and Identification of(3Z,6Z,8E)-3,6,8-dodecatrien-1-ol in Reticulitermes santonensis Feytaud(Isoptera, Rhinotermitidae): Roles in Worker Trail-Following and inAlate Sex-Attraction Behavior,” J. Insect Physiol., vol. 40, pp. 781-787(1994).

Termites have also showed trail-following activity in response tocertain non-pheromone chemicals. The trail-following activity of severalsynthesized (Z)4-phenyl-3-buten-1-ol derivatives has been tested forfive species of subterranean termites in the genera of Coptotermes,Reticulitermes, and Schedorhinotermes. See G. Prestwich et al.,“Structure-activity relationships among aromatic analogs of thetrail-following pheromone of subterranean termites,” J. Chem. Ecol.,vol. 10, pp. 1201-1217 (1984).

Several glycol compounds have been reported to act as trail followingsubstances for termites. G. Becker et al., “Untersuchungen über dasverhalten von Termiten gegenüber einigen spurbildenden Stoffen,” Z.Angem. Entomol., vol. 53, pp. 400-436 (1968). (See English languagesummary, pp. 433-434.)

M. Rust et al., “Enhancing Foraging of Western Subterranean Termites(Isoptera: Rhinotermitidae) in Arid Environments,” Sociobiology, vol.28, pp. 275-286 (1996) reported that foraging of the westernsubterranean termite Reticulitermes hesperus was enhanced by placinginto sand extracts from the brown rot fungus Gloeophyllum trabeum, andthat the fungal extract plume in the soil could assist worker termitesin locating monitoring or bait stations.

J. Gassett et al., “Volatile Compounds from the Forehead Region of MaleWhite-Tailed Deer (Odocoileus virginianus),” J. Chem. Ecol., vol. 23,pp. 569-578 (1997) reported several compounds identified in secretionsfrom the forehead and back of the male white-tailed deer, includingnaphthalene.

Papermate® ball-point pen ink is known to elicit trail followingbehaviors in introduced Formosan subterranean termites and nativesubterranean termites. (Harry McMennemy, private communication.)However, the active ingredient has not previously been identified.

DISCLOSURE OF INVENTION

We have discovered several previously unknown components of termite nestcartons. These compounds may be used as an attractant for termite baits,as a feeding stimulant, as the basis for novel chemical methods ofdetecting termite nests, and as the basis for novel biological methodsof controlling termites.

As one example of these newly-discovered components, we have for thefirst time identified and quantitatively measured naphthalene as acompound present in termite cartons. Naphthalene has been identified incolonies from Florida, Hawaii, and Louisiana by gas chromatography-massspectrometry (GC-MS).

MODES FOR CARRYING OUT THE INVENTION EXAMPLE 1

Termites and Nest Carton Materials

Termites with their nest cartons were collected from colonies infestinghouses and trees in New Orleans, Lake Charles, Houma, Slidell, Algiers,and Gretna, La. Collected termites were kept at room temperature (23-28°C.) in plastic or aluminum trash cans with pine wood stakes andcorrugated cardboard. Nest carton from a colony in Honolulu, Hawaii wasprovided by Dr. J. K. Grace and Mr. J. Wang. Nest carton from a colonyin Largo, Fla. was supplied by Mr. G. D. Gordon. The cartons from Hawaiiand Florida were stored at 4° C. until analysis.

EXAMPLE 2

Measurement of Naphthalene in Termite Nest Carton

Naphthalene was quantitatively measured in the colonies of Example 1from Florida, Hawaii, and New Orleans, La. One-half kilogram cartonmaterial from the Hawaiian or Louisiana carton, and all of the availablecarton from the Florida collection (about 400 g each) were ground into apowder using a ceramic mortar and pestle. Three 50-gram sub-samples wereextracted with 50 mL hexane three times; and 50 μL azulene (99+%, SigmaChemical Co., St. Louis, Mo.) in hexane solution at a concentration of0.178 mg/mL were added to each sample as an internal standard. Thepooled extract was concentrated to 0.1 mL using a rotary evaporator andnitrogen flow. The extract was then analyzed by GC-MS. As a control, 150ml of hexane were concentrated to 0.1 mL and analyzed for naphthalene.Rates of loss by evaporation were equivalent for azulene andnaphthalene.

Nest carton material from five Louisiana colonies (one each fromAlgiers, Houma, and Slidell, and two colonies from New Orleans) werequalitatively analyzed for naphthalene. Six hundred grams of cartonmaterial from each colony were ground and extracted with 350 mL hexanethree times. Pooled extracts were concentrated to 1.5 mL with a rotaryevaporator and nitrogen flow, and were filtered with hexane through a 5cm×0.3 cm silica gel, 70-230 mesh (63-200 μm), average pore diameter:60Å, Sigma Chemical Co., St. Louis, Mo.). The first 4 mL were collected,concentrated to 0.3 mL under nitrogen flow, and analyzed by GC-MS. Onethousand fifty mL of hexane were concentrated to 0.3 mL and analyzed asa control for naphthalene in the solvent.

The naphthalene retention time was 7.85 min. with the GC-MS systemdescribed below. Naphthalene levels in carton nests ranged from about100 μg/kg in Louisiana colonies, to about 250 μg/kg in Hawaiiancolonies, to about 500 μg/kg in Florida colonies. The mass spectrum andGC retention time of 7.85 minutes both matched a naphthalene standard.Naphthalene was not detected in the solvent control samples, but wasfound in nest carton materials from all five colonies analyzed.

Following is a description of the analytical techniques used in thisExample 2. Unless otherwise indicated, generally similar analyticaltechniques were used in the other Examples. Naphthalene analysis ofcarton nest was conducted by GC-MS using a Hewlett Packard 5890 GasChromatograph with a 5971A Mass Selective Detector (a quadrupole massspectrometer using 70 eV electron impact ionization). The GC wasequipped with a DB-5MS column (20 m long, 0.18 mm i.d., film thickness0.18 μm, J&W Scientific, Folsom, Calif.). The initial temperature was50° C. for 3 min., programmed at 20° C./min. to 280° C., which was heldfor 25 min.

Naphthalene was identified by comparison of mass spectra and GCretention times of peaks in the sample with those of a naphthalenestandard (99+%, Sigma Chemical Co., Missouri).

EXAMPLES 3-7

Antifungal Activities of Compounds Associated With Formosan Termites

Five compounds that we isolated from the nests and bodies of Formosansubterranean termites were evaluated to determine their effect on aMucor spp. fungus that is associated with termites and termite nests. Ofthe five compounds tested, naphthalene was most effective at inhibitingthe growth of this fungus. We believe that one function of naphthalenein termite nests is to inhibit pathogenic fungal growth.

The humid conditions of termite nests and galleries are ideal for thegrowth of several species of fungi. Some of these fungi are beneficialto termites, aiding in the breakdown of cellulose or providingadditional nutrients, while other fungi are toxic or pathogenic totermites. Fungi are found more often in wood with termite galleries thanin wood without termite galleries, suggesting that termites bothintroduce fungi to the wood, as well as help spread fungi that arealready present. Mucor species, so-called sugar fungi, are commonlyassociated with dung, leaf lifter, and other decaying organic matter.

Our research group has often observed a white fungus flourishing ontermite nests within one week of our collecting a nest in the field andbringing it into our laboratory. Nests with such visible fungal activityinvariably contain large numbers of sick and dying termites. This fungushas presented substantial obstacles to maintaining collected termitecolonies in our laboratory for research purposes. We recently identifiedthe fungus as a Mucor spp.

Mucor was isolated from a Formosan termite nest in our laboratory, anest originally collected from a cottonwood tree in New Orleans, La. Thefungus comprised a white mat that covered large areas of the nest thathad been exposed to air and water. Fungus was scraped from the nest andsuspended in distilled, de-ionized water with a Pasteur pipette. Thissuspension was streaked on Sabouraud dextrose agar (“SDA”) (DifcoLaboratories, Detroit, Mich.) in 100×15 mm plates containing 20 mL SDA.Pure cultures were obtained from individual colonies on these plates asneeded. Cultures were maintained on SDA plates in a 27° C. incubatorwithout light until used.

Filter paper disks (Whatman #1, 1.5 cm) were treated with naphthalene,butylated hydroxytoluene (BHT), dioctyl phthalate, or adipic dioctylester, at rates of 2 μg, 20 μg, or 200 μg, dissolved in 100 μL hexane.Controls were treated with hexane alone. For each treatment, just priorto testing for antifungal properties, 1 mL of the hexane solution andten filter paper disks were placed in a vial, and N₂ was used toevaporate the hexane.

A suspension was prepared by scraping Mucor conidia (spores) from theculture plates, and mixing into distilled, deionized water with aPasteur pipette. A thin layer of this suspension was spread over thesurface of each of 130 SDA plates by placing each plate onto aninoculation turntable (Fisher Scientific, Hampton, N.H.), pipetting 0.2mL of the suspension into the center of the plate, spinning theturntable, and spreading the suspension onto the agar with a bent glassrod. The plates were allowed to dry for two hours. A treated filterpaper disk was then placed in the center of each plate (10plates/treatment), and the plates were incubated at 27° C. The extent towhich each filter paper disk was covered by fungus was determined byvisual inspection (by the method described in greater detail below)after four, five, and six days.

A second trial was conducted with filter papers treated withnaphthalene, BHT, or 2,6-di-t-butyl-4-methyl-phenol (“DBP”). A fungalsuspension was prepared as in the first trial. Spore concentrations weredetermined with a counting chamber (Petroff-Hauser, Hauser ScientificPartnership, Horsham, Pa.). Concentrations were adjusted toapproximately 10⁷ spores/mL. In the first trial fungus grew on SDAquickly, forming a thick mat that soon filled the entire petri dish.Therefore, in the second trial cornmeal agar (CMA, Difco Laboratories,Detroit, Mich.) was used to slow the growth of the fungus during thesix-day observation period. A thin layer of the spore suspension wasspread over the surface of each of 24 cornmeal agar plates using aturntable and bent glass rod, as previously described.

Filter paper disks were treated with naphthalene, BHT, or DBP at ratesof 2 μg, 20 μg, or 200 μg, prepared as in the first trial. On each platewere placed four filter paper disks spaced equidistant from one another(one disk containing each of the three application rates of one of thetest compounds, and one disk containing only the hexane control). Eachplate was then covered and sealed with parafilm to reduce the release ofvolatile compounds. The concentration of naphthalene in the headspacewas 0.04 μg/cm³; except in trial 3 below, in which the concentration was34.6 μg/cm³, about 700 times the concentration we have observed intermite nest materials. The growth of fungus on and around each filterpaper disk was recorded three, four, and five days after treatment. Theexperiment was then repeated, increasing the rates of naphthalene, BHT,and DBP to 200 μg, 600 μg, and 1000 μg (trial 3).

Fungal growth on each filter paper disk was recorded by making tracingsof the disks, inking in areas with visible fungal growth. The fractionof each disk covered by fungus was measured by making photocopyenlargements of these drawings, cutting out the enlarged disks, weighingthe entire circle, cutting out the inked areas of the circle(corresponding to fungal growth), and weighing the latter. The fractionof each circle covered with fungus was then calculated as the ratio ofthese weights. (The weight of the photocopy toner was negligible.)

Coverage of filter paper disks was analyzed by the ANOVA procedure (SASInstitute, Version 6.11, Cary, N.C.). Tukey's Studentized Range (HSD)Test was used for comparison of mean separations (α=0.05).

In the first trial, the growth of fungus on the treated filter paperdisks did not differ significantly from the growth on control disks. SeeTable 1.

TABLE 1 Mean percentage of filter paper disk surface covered by fungus,trial 1. Fraction Fraction Fraction covered, covered, covered, CompoundRate Day 4 Day 5 Day 6 Naphthalene  2 μg 71% 86% 98%  20 μg 64% 97%100%  200 μg 90% 92% 100%  BHT  2 μg 70% 85% 92%  20 μg 27% 65% 76% 200μg 28% 56% 93% Dioctyl phthalate  2 μg 67% 78% 89%  20 μg 32% 49% 88%200 μg 57% 69% 82% Adipic dioctyl ester  2 μg 44% 83% 94%  20 μg 20% 80%62% 200 μg 20% 75% 91% Control  0 μg 50% 88% 93%

In trials 2 and 3, where conditions favored slower growth, filter paperscontaining all concentrations of a particular compound were placed ontothe same agar plate. Therefore, when comparing the significance ofdifferent results from different compounds, all concentrations of thesame compound were grouped together and considered as a singletreatment. In trial 2, filter paper coverage was greater than 90% afterthree days for all compounds. See Table 2.

TABLE 2 Mean percentage of filter paper disk surface covered by fungus,trial 2. Fraction Fraction Fraction Covered, Covered, Covered, CompoundRate Day 3 Day 4 Day 5 Naphthalene  0 μg 98% 99% 95%  2 μg 100%  99%100%   20 μg 98% 98% 99% 200 μg 100%  100%  100%  BHT  0 μg 93% 94% 96% 2 μg 85% 90% 90%  20 μg 93% 95% 98% 200 μg 95% 99% 100%  DBP  0 μg 96%100%  100%   2 μg 98% 99% 99%  20 μg 92% 95% 98% 200 μg 81% 91% 99%

In the third trial, where application rates increased to a maximum of1000 μg, no fungal growth was seen on the filter paper disks for any ofthe naphthalene treatments. See Table 3. Three days after treatment,coverage of filter paper was significantly greater in the BHT treatmentsthan in either the DBP or naphthalene treatments (P=0.0001). By thefourth day, fungal coverage of both the BHT- and the DBP-treated disksapproached 100%, while there was still no growth on the naphthalenetreated disks. When plates were examined eight days after treatment, thedisks treated with naphthalene were still free of fungus.Since“naphthalene disks” inhibited fungal growth at all rates ofapplication (including the 0 μg application), the fungicidal activitywas apparently due at least in part to fumigation by naphthalene vapor,instead of (or perhaps in addition to) contact with the solid phasenaphthalene.

TABLE 3 Mean percentage of filter paper disk surface covered by fungus,trial 3. Fraction Fraction Fraction Covered, Covered, Covered, CompoundRate Day 3 Day 4 Day 5 Naphthalene  0 μg  0%  0%  0% 200 μg  0%  0%  0%600 μg  0%  0%  0% 1000 μg   0%  0%  0% BHT  0 μg 59% 100%  100%  200 μg30% 96% 95% 600 μg 53% 97% 100%  1000 μg  16% 99% 100%  DBP  0 μg 40%100%  100%  200 μg  0% 94% 93% 600 μg 1% 100%  100%  1000 μg   0% 91%97%

EXAMPLE 8

Eliminating Natural Termite Defense Barriers

Although some fungi are beneficial to the termite colony, excessivefungal growth can cause termite death. Combined with other defensemechanisms, such as labial gland secretions, termites may usenaphthalene fumigation as an important mechanism to suppress the growthof fungi in their nests. In healthy termite colonies, fungal growth issuppressed, at least in part, by naphthalene in air spaces in the nests.However, in disturbed colonies natural barriers are broken, allowing airto enter the nest more freely. This elimination of a natural defensemechanism explains the fungal mats that we have often seen aftercolonies have been transported from the field to the laboratory. Wepropose that one way to exterminate at least some termite colonies is tocreate conditions encouraging the flow of volatile naphthalene (andperhaps other volatile compounds) away from the termite nest. This goalmight be achieved, for example, by one of more of the followingtechniques: placing many holes in the termite nest, forcing air throughthe nest with a fan, or forcing water into the nest. These methods ofincreasing the outward flow of volatile compounds may be used alone, orin conjunction with other methods of exterminating termite colonies.

EXAMPLE 9

2-phenoxyethanol as a Trail-following Compound

We have isolated and identified 2-phenoxyethanol as the compound inPapermate® ball-point pen ink that elicits trail-following activity intermites. 2-phenoxyethanol elicited trail-following behaviors in both C.formosanus Shiraki and Reticulitermes spp. Holmgren.

Papermate® ball-point pens were purchased from an Office Depot store inBaton Rouge, La. C. formosanus were collected from a colony in NewOrleans, La. Reticulitermes spp. were collected from a colony in BatonRouge, La. Collected termites were kept at room temperature (23-28° C.)in plastic containers (20 cm diam., 20 cm height) with sand (#4 blastingsand) and moistened corrugated cardboard.

Ink was removed from 30 ball-point pens into 200 mL 5% ethanol. The inksolution was extracted with 200 mL hexane three times. The upper(hexane) layers were collected, filtered through a filter paper (Whatman1, qualitative, 15.0 cm), and then concentrated to 5 mL under reducedpressure. The extract was placed on a glass column (5 cm long, 2 cmi.d.) packed with silica gel (70-230 mesh, 60Å average pore diameter,Sigma Chemical Co., St. Louis, Mo.). The column was successively elutedwith 100 mL hexane and 400 mL of a 50%/50% mixture of acetyl acetate andhexane. The acetyl acetate-hexane elution was collected and concentratedto 2 mL under reduced pressure. This fraction was further fractionatedby high-performance liquid chromatography with a normal-phaseSupelcosil™ LC-Si column (25 cm×4.6 mm, 5 μl particle size, 100Å poresize). Elution was performed with hexane-dichloromethane in gradientmode at a flow rate of 1.0 mL/min. The solvent composition wasprogrammed as follows: 100% hexane for the first 20 min., then changedover 20 min. linearly from 100% hexane to hexane-dichloromethane90%:10%, then linearly changed over 30 min. from hexane-dichloromethane90%:10% to 100% dichloromethane, and kept at that composition for 10min. The column was cleaned by running with 100% dichloromethane formore than 20 min. between runs. One fraction was collected every twominutes (for a total of 40 samples). Each fraction was concentrated into0.3 mL under nitrogen.

The high-performance liquid chromatograph (HPLC) was a Ranin RabbitHP/HPX Solvent Delivery System with two Ranin Pump Heads (10 mL). AKnauer Variable Wavelength Monitor was used as a detector. The GC-MSused was a Hewlett Packard 5890 Series II gas chromatograph, coupledwith a Hewlett Packard 5971A mass-selective detector. The GC wasequipped with a capillary DB-5 column. The injection temperature was250° C. The oven temperature was kept at 50° C. for the first 2 min.,then programmed at 20° C. per min to 280° C., and held at 280° C. for6.5 min. Helium carrier gas was delivered at a velocity of approximately40 cm/sec. The ion source temperature was 200° C., and the ionizationvoltage was 70 eV.

C. formosanus workers were used in the initial bioassay fortrail-following behavior. The trail-following bioassay was conducted ontwo overlapped pencil circles of radius 3 cm. The circumference of eachcircle passed through the center of the other circle. Each sample wasstreaked along one of the circles with a 4 μl-micropipette onnonabsorptive paper. A solvent (control) was streaked along theoverlapping circle. After the solvent evaporated, one worker was placedin the center of overlap between the two circles. The arena was coveredwith a red plastic container to reduce visible light and extraneous airflow. To score the worker's activity, one point was given for eachcontinuous 3 cm traveled by a termite over a one minute period. Threereplications were performed for each fraction. A new termite was usedand new circles were drawn for each trial. A fraction was consideredinactive if no points were assigned; it was considered moderately activeif, on average, termites followed the circle between 3 to 6 cm; and wasconsidered very active if termites followed the trail for 6 cm or more.

HPLC Fraction 34 was moderately active. Fractions 35 to 40 were veryactive. Eight fractions, numbers 29 to 36, were selected for individualGC-MS analysis to identify increases in the active compound(s)responsible for trail-following activity. This set of neighboringfractions, covering the transition from inactive fractions to activetrail-following fractions, was chosen to yield information that could behelpful in identifying the active peak(s), and in ruling out compoundsthat might co-elute during the active period but that lackedtrail-following activity. Compounds were identified by comparingGC-retention times and mass spectra to those of standards.

A peak with retention time 8.10 min. was seen in each of the eight HPLCfractions selected for GC-MS analysis. The 8.10 minute peak wasespecially strong in fractions 34 to 36. A computer library search, andcomparison of mass spectra and retention times with a standard compound,confirmed that this peak was 2-phenoxyethanol.

Trail-following bioassays with standard 2-phenoxyethanol followedprocedures that were essentially identical to those for the HPLCfraction screening bioassay described above, except that each trial wasreplicated 10 times; and that workers and soldiers of both C. formosanusand Reticulitermes spp. were tested. Four concentrations of2-phenoxyethanol, 0.32, 0.032, 0.0032, 0.00032 μg/cm were used in thebioassays.

2-phenoxyethanol elicited trail-following behaviors in C. formosanusworkers and soldiers, and also in Reticulitermes spp. workers andsoldiers at concentrations of 0.32 μg/cm, 0.032 μg/cm, and 0.0032 μg/cm.Limited trail-following activity at 0.00032 μg/cm was also seen.

2-phenoxyethanol shares little structural similarity to the naturaltermite trail pheromone of Formosan subterranean termites, except thatboth are primary alcohols.

EXAMPLES 10-36

Other Potential Attractants, Stimulants, and Reporter Molecules

The molecules identified in Examples 10-73, derived from termite nestcarton, are potential termite attractants or feeding stimulants, orpotential reporter molecules to identify the presence of termitecolonies.

Analyses generally similar to those described above for Examples 1 and 2have identified several other compounds from termite carton materials,some of which have activity as feeding stimulants, attractants, anddefensive chemicals. (Bioactivity testing of these compounds isongoing.) Compounds that we have identified in Formosan termite nestcartons included arenes, esters, organic acids, sterols, and long-chainhydrocarbons.

The arenes identified included naphthalene and BHT.

The organic acids identified included hexanoic acid; octanoic acid;nonanoic acid; undecanoic acid; nonanedioic acid; dodecanoic acid;tetradecanoic acid; pentadecanoic acid; hexadecanoic acid; heptadecanoicacid; 14-methyl-hexadecanoic acid; (Z,Z)-9,12-octadecadienoic acid;octadecanoic acid; 6-octadecenoic acid; 2-octyl-cyclopropaneoctanoicacid; eicosanoic acid; docosanoic acid; and tetracosanoic acid.

Sterols identified include 3-β-dihydrocholesterol;(24s)-stigmast-5-en-3-ol; and methyl(3-β,5-α)ergostan-3-ol. A feedingbioassay on an ergosterol standard showed that ergosterol alsostimulated the feeding of Formosan termites. The bioassay was conductedaccording to the general procedures of U.S. application Ser. No.08/243,950, filed May 17, 1994.

Esters identified include hexanedioic acid dioctyl ester; dioctylphthalate; and dibutyl phthalate.

EXAMPLES 37-73

Solid Phase Extraction of Nest Carton Components

Microwave Distillation-Solid Phase Microextraction (MD-SPME) combinedwith gas chromatography-ion trap mass spectrometry was also used toextract and identify components of nest carton, using a modification ofan analytical technique developed by S. W. Lloyd and C. C. Grimm of theSouthern Regional Research Center, United States Department ofAgriculture, Agricultural Research Service.

Twenty five grams of carton material were placed in a 100 mL roundbottom flask inside a standard 800 W microwave oven. A double offsetinlet adapter was connected to the flask. Each opening on the adapterheld a Teflon™ tube. Both tubes exited through a hole in the side of theoven. One tube was connected to a nitrogen gas cylinder, and the otherwas inserted into a 20 mL graduated cylinder placed in a −14° C. cooler.The oven ran at 50% power for 3 min. to heat the sample, while nitrogenflowed through the flask at 80 mL per minute. The volatilized componentsand water vapor condensed in the −14° C. 20 ml graduated cylinder. Thecondensate was diluted to 8 mL with water, and poured into a 10 mL vialalong with 3.0 g NaCl and a stir bar. The vial was then covered withTeflon tape and placed in a 40° C. water bath with magnetic stirring. Asolid-phase microextraction fiber (Sulpelco, Inc., Bellefonte, Pa.) witha 100 μm polydimethylsiloxane phase was exposed to the headspace in thevial for 30 min. A GCQ™ gas chromatography-mass spectrometer was used toanalyze the volatiles. The results appear below, with the most likelycandidates for each peak identified by a computerized library searchagainst measurements of known standards.

TABLE 4 Peak number, Retention time (min) Probable composition 1, 3:55Ethanedione, diphenyl- Benzoyl isothiocyanate Benzoyl chloride 2, 5:50Benzene (methoxymethyl) Phenylethyl alcohol Benzaldehyde,3-benzyloxy-2-fluro-4-methoxy- 3, 6:20 1,3-Dioxolane,4-pentyl-5-propyl-2, 2-bi(trifluoromethyl)-, cis-Cis-9,10-Epoxyoctadecan-1-ol Cyclopentane, 1-hexyl-3-methyl- 4, 6:432-Furanmethanol, 5-ethenyltetrahydro-α,α, 5-trimethyl-6-Nonynoic acid,methyl ester 3-Nonynoic acid, methyl ester 5, 7:48(R)-(−)-(2)-14-methyl-8-hexadecen-1-ol (Z)-6-pentadecen-1-ol 9-Eicosyne6, 7:58 2,5-Heptadien-4-one, 2,6-dimethyl- Bicyclo[2.2.2]octane,1-bromo-4-methyl Bicyclo[2.2.2]octane, 1-methyl-4- (methylsulfonyl)- 7,9:04 p-Menth-4(8)-en-9-ol Cyclopropane, trimethyl(2-methyl-1-propenylidene)- Bicyclo[6.1.0]nonane,9-(1-methylethylidene)- 8, 9:45 cyclohexamethanol, 4(1-methylethyl)-,cis- 3-Heptadecen-5-yne, (Z)- 9,1-2,15-Octadecatrien-1-ol 9, 10:11[4.2.2]propella-2,4,7,9-tetraene Naphthalene Azalene 10, 11:29(R)-(−)-(Z)-14-Methyl-8-hexadecen-1-ol (Z) 6-Pentadecen-1-ol 3-Eicosyne11, 13:37 2-naphthalenol, decahydro- 2) 13-octadecenal (Z)- 3)cyclohexanol, 5-methyl-2-(1-methylethenyl)- 12, 13:58 1,3-Benzenediol,5-pentadecyl- 1,3-Benzenediol, 5-pentyl- 2-Cyclohexen-1-one,4-hydroxy-3,5,6-trimethyl-4- (3-oxo-butenyl)- 13, 14:22Bicyclo[2.2.1]heptane, 2-chloro-2,3,3-trimethyl- Bicyclo[2.2.1]heptane,2-chloro-1,7,7-trimethyl-, exo- Bicyclo[2.2.1]heptane-2-ol,1,3,3-trimethyl-, acetate, endo- 14, 14:53 Menth-1(8)-ene 8-HexadecyneCyclohexane, 1-methyl-4-(1-methylethylidene)- 15, 15:13 Benzene,1-hexynyl- Benzene, 1-cyclohexen-1-yl- Benzene, [(1-methylethylidene)cyclopropyl]-, (R)- 16, 15:29 (R)-(−)-(Z)-14-methyl-8-hexadecen-1-ol3-Eicosyne (Z) 6-Pentadecen-1-ol 17, 15:47 Cyclopentane,1-methyl-2-methylene- Menth-1(8)-ene Cyclohexane,1-methyl-4-(1-methylethylidene)- 18, 16:573-Acetyl-2,4,4-trimethylcyclohex-2-en-1-one Phosphonic acid, 7-octenyl-,diethyl ester 20, 17:11 N-Ethyl-6-propyl-6-dodecanamine4H-1-Benzoselenin-4-one, 2,3-dihydro- 1H-Carbazole-Z-ethylamine,3-ethyl-2,3,4,9-tetrahydro-N,N,1- trimethyl- 21, 17:43 10-undecenal13-tetradecenal undecenal 22, 17:54 Propanoic acid, 2-methyl-,3-hydroxy-2,4,4-trimethylpentyl ester Propionic acid, 2-menthyl,2-ethyl-3-hydroxyhexyl-ester 2,4,6-Trimethyldecane-1,3,10-triol 23,18:33 4a(2H)-Naphthalenol, octahydro-4,8a-dimethyl- (4α,4aα,8αβ)-trans-1, 10-Dimethyl-trans-9-decalol 1,2-cyclohexanedicarboxaldehyde 24,19:26 3-Eicosyne (Z) 6-Pentadecen-1-ol Cyclohexanol,5-methyl-2-(1-methylethyl)-, (1α,2β,5α)- 25, 20:12 Camphorsulfonic acid2H-Inden-2-one, 1-bromooctahydro-7a-methyl-, (3aα,7aβ)1H-benzocycloheptan-7-ol,2,3,4,4a,5,6,7,8-octahydro-1,1,4a,7-tetramethyl, cis- 26, 21;13 1,6,10-Dodecatrien-3-01,3,7,11-trimethyl-(E)- Cyclohexane,1-ethenyl-1-methyl-2-(methylethenyl)-4-1-methyl) Germacrone B 27, 21:262,5-Cyclohexadiene-1,4-dione,2,6- bis(1,1-dimethyethyl)-2H-2,4a-Ethanoaphthalen-8(5H)-one, hexahydro-2,5,5-trimethyl-3-Buten-2-one,4-(2,6,6-trimethyl-1-cyclohexen-1-yl)- 28, 22:08 phenol,(1,1-dimethylethyl)-2-methoxyl Benzenethiol,4-(1,1-dimethylethyl)-2-methyl- 31, 25:57 γ-Gurjunene1H-cycloprop[e]azulene, decahydro-1,1,7- trimethyl-4-methylene-,[−]-A-Selinene 32, 29:35 Cyclohexane, (2,2-dimethylcyclopentyl)-Cyclopentadecenol (Z) 6-Pentadecen-1-ol 33, 30:14 Altretamine1,1-Biphenyl,2,2-diethyl- 34, 30:30 Heptadecane, 2,6,10,15-tetramethylTritetracontane Hexadecane, 2,6,11,15-tetramethyl 35, 30:421-Dotriacontanol Heneicosyl formate 1-Hexadecanol,3,7,11,15-tetramethyl- 36, 30:52 2(1H)-Benzocyclooctenone,decahydro-10a-methyl, -trans Benzocyclodecane, tetradecahydro-9-Eicosyne 37, 31:27 1,1-Bisphenyl,2,2′-diethyl- Benzene,1,1′-methylenebis[4]-methyl- Benzene 1,2-dimethyl-4-(phenylmethyl)-

EXAMPLES 74-84

By taking samples from air pumped from a termite nest, other volatilecompounds from termite nests have been identified. One end of a Tenax™short path thermal desorption tube was connected to a pump. The otherend of the tube was connected to metal tubing, which was in turninserted into a termite nest. After 30 minutes, the pump was turned off,and the sample was analyzed by a GC-MS instrument equipped with a shortpath thermal desorption apparatus. The volatile compounds thusidentified included the following:

δ-3-carene

2,3,7-trimethyloctane

2,6,10-trimethyldodecane

elemene

α-longipinene

aristolene

calarene

β-guaiene

N-(1-methylhexylidene)-methylamine

2,6,10,14-tetramethylpentadecane

α-muurolene

fenchone

The last item on this list, fenchone, is known to have properties as aninsecticide and fumigant. As with naphthalene, termites may use fenchoneto repel other organisms such as ants from the nest.

In a preferred embodiment, an effective amount of a feeding stimulantcomprising one or more of the compounds selected from the groupconsisting of DBP, naphthalene, hexanedioic acid dioctyl ester, anddioctyl phthalate are mixed with a toxicant for termites, preferably byimpregnating both the stimulant and the attractant into a termite baitsuch as cardboard. Other preferred feeding stimulants include ergosteroland its analogs (such as steroids specific to yeasts and other fungi).Preferred attractants that may be used in conjunction with feedingstimulants include 2-phenoxyethanol; naphthalene;3,5-di-tert-butyl-1,2-benzoquinone; 1,1-dimethylethyl-2-methoxyphenol;and 3-carene and its analogs (such as wood-derived terpenes). When theimpregnated bait is placed in the vicinity of a termite colony, termiteswill preferentially feed on the treated bait, thereby consuming thetoxicant, and typically thereafter introducing the toxicant to othermembers of the colony as well. Not only do these stimulants increasefeeding activity, but they can also increase the durability of the bait:(1) by excluding natural enemies of termites (such as fire ants) fromthe bait; and (2) by inhibiting deterioration of the bait matrixmaterial. BHT is an antioxidant and preservative. Naphthalene is acommon arthropod fumigant, antiseptic, and anthelmintic agent; dioctylphthalate and hexanedioic acid dioctyl ester are antimicrobial agents.Despite these activities, these agents are naturally associated withtermites. Thus use of these agents in termite bait can both increasebait acceptance, and increase durability of the bait. No single compoundhas previously been reported to have such dual activity in a termitebait.

Optionally, one or more free amino acids may also be added to thetermite baits to further stimulate feeding, preferably aspartic acid,glutamic acid, or proline. See U.S. patent application Ser. No.08/243,950, filed May 17, 1994.

Formosan termites deposit BHT on their food, presumably to help preserveit. We have observed that BHT is even more effective than naphthalene atkilling ants. BHT may also help preserve termite trail pheromone. Theinstability of the trail pheromone has previously been a limiting factorin the use of pheromones or trail-following substances in termite baits.Adding BHT or another antioxidant to known pheromones will allowpheromones or trail-following substances to be used in baits.

An alternative is to place a volatile attractant or feeding stimulantbehind a semi-permeable membrane, so that the volatile attractant orstimulant “leaks” out slowly in the field. Examples of suitablesemi-permeable membranes include parafilm, paper, waxed paper,nitrocellulose, nylon 66, and gelatin.

Another application of this invention is to detect carton-associatedcompounds in the field, to identify the presence and location of termitenests. For example, naturally-occurring naphthalene is rare in mostareas. Thus field detection of naphthalene can be a fairly specificindication of the presence of a termite nest (after excluding, ifnecessary, artificial sources of naphthalene such as moth balls). Fielddetection may be performed, for example, with a portable gaschromatograph such as that disclosed in U.S. Pat. No. 5,611,846.

A related application is to trap volatile compounds over a period oftime, e.g. over a period of hours to months, and have the trappedvolatiles analyzed by an off-site laboratory for reporter moleculesindicating the possible presence of a termite colony. For example, aninexpensive device for this purpose could be placed in the home,comprising a small air pump and a trap made from an absorbent materialsuch as Tenax™. Other suitable adsorbents include silica gel,Hopcalite™, charcoal, and polyethylene foam. In a preferred embodiment,the sampling device is adapted to pump air from the interior of a wall,floor, ceiling, roof, or eave through an electrical, telephone, cable,or lighting outlet, or through a vent. The air from the interior of awall is likely to have higher concentrations of volatile compoundsassociated with termite nests, both because termite nests and sheltertubes tend to be found in such regions, and also because air circulationis lower in these confined spaces. Pumping air from an existing outletor vent avoids the need to drill holes into walls to sample such areas.Preferably, the pump and adsorbent are incorporated into a small unitthat plugs into and remains in place in an electrical socket,superficially similar to units such as carbon monoxide detectors soldfor use in the home. Air is drawn from a second socket in the sameelectrical outlet, for example through a cup positioned over the secondsocket, or through non-conductive tubes shaped to be inserted into thesocket and pull air from inside the outlet. The pump is preferablyoperated by current from the same outlet; but alternatively could beoperated by batteries. In an alternative embodiment, an adapter holdingthe adsorbent is mounted onto a vacuum cleaner, and the vacuum cleaneracts as the pump to pull air from the interior region across theadsorbent.

In household applications, naphthalene is preferred reporter molecule.Other volatile compounds identified in the nest may also be used,including terpenes and terpenoids. Of these compounds, fenchone appearedin our data most consistently, and is considered especially promising.

Naphthalene has never previously been reported to occur naturally inassociation with termites, nor indeed with any insects or otherinvertebrates. Naphthalene at concentrations of 0.1 to 0.5 mg/kg (ormore) in termite cartons may constitute (at least in part) a uniquechemical defense strategy. A termite nest is a partially closed systemthat protects termites from air movement and provides a controlledmicroclimate. This semi-closed system may allow termites to usefumigation as a defense strategy. Such nest fumigation may repelinvertebrates and other animals from entering the carton nests. In fact,we have found that Formosan subterranean termites have a highertolerance to naphthalene than that of one of their natural enemies,ants.

We have compared the effect of naphthalene on C. formosanus and on theimported red fire ant, Solenopsis invicta Buren. We found that C.formosanus had significantly higher tolerance to naphthalene than did S.invicta. Ants were paralyzed at naphthalene concentrations that causedno visible effect on termites. Naphthalene fumigation of nests may playan important role in defending termite nests from predation by ants.

Naphthalene is an antimicrobial and anthelmintic agent. Soil-dwellingFormosan termites confront many adversaries, including ants, fungi,bacteria, and nematodes. Ants are known to secrete compounds withantimicrobial ability to help them succeed in soil habitats. Formosansubterranean termites may use a similar strategy. Fumigating the nestwith naphthalene may play an important role in inhibiting microorganismsand nematodes.

The origin of the naphthalene in nest carton is currently unknown.Naturally-occurring naphthalene has previously been reported from coal,petroleum, incomplete combustion of organic materials from forest fires,and Magnolia flowers. Naphthalene is a common arthropod fumigant (e.g.,against clothes moths), and has been used as a repellent against bats,pigeons, sparrows, squirrels, starlings, and rabbits. Since termites usesoil, masticated wood, and excrement to make their nests, a possiblesource of naphthalene is processed food or soil. However, a literaturesearch indicated that naphthalene is not present in wood, although wooddoes contain several potential precursors for naphthalene. Naphthalenehas never been reported as a natural constituent of any type of soil.Although the possibility of soil pollution with naphthalene cannot beexcluded, it seems unlikely that the widely dispersed termite nestsexamined in these experiments were all contaminated by artificialsources of naphthalene. Another possible origin for naphthalene ismicrobial biosynthesis in the termite nest, gut, or on the food.However, a literature search found no prior reports of naphthalenebiosynthesis by any microorganisms or invertebrates.

As used in the specification and in the claims, an “effective amount” ofa feeding stimulant is an amount that, when mixed with a termitetoxicant in a bait, will increase the rate of consumption of thetoxicant by termites to at least ten percent above the rate ofconsumption of an otherwise comparable bait lacking the feedingstimulant.

As used in the specification and in the claims, an “effective amount” ofan attractant is an amount that, when placed in the vicinity of a baitcontaining a termite toxicant in a bait, will increase the rate ofconsumption of the toxicant by termites to at least ten percent abovethe rate of consumption of an otherwise identical bait placed in theabsence of the attractant.

Preferred toxicants are slow-acting, to avoid “learning” effects beforeindividuals have distributed food to other members of the colony.Several slow-acting toxicants for termites are known in the art, andinclude, for example sulfluramid, avermectin, hydramethylnon,hexaflumuron, fipronil, and diflubenzuron.

Preferred termite bait materials include cardboard, paper, sugar cane,corn cobs, and dried semi-aqueous cellulose mixtures. An alternative toimpregnation of the bait is to manufacture paper or cardboard containingthe toxicant and feeding stimulant in the paper or cardboard from thebeginning. Adding moisture to the bait can help increase itsattractiveness to termites. Attractants (especially water-solubleattractants) may optionally be added to the soil to draw termitestowards the bait.

The complete disclosures of all references cited in this specificationare hereby incorporated by reference. In the event of an otherwiseirreconcilable conflict, however, the present specification shallcontrol.

What is claimed:
 1. A combination for killing termites, comprising atermite toxicant and an effective amount of a feeding stimulantcomprising at least one compound selected from the group-consisting of2,6-di-t-butyl-4-methyl-phenol; naphthalene; ergosterol; hexanedioicacid dioctyl ester; and dioctyl phthalate; wherein an effective amountof said feeding stimulant is an amount that will increase the rate ofconsumption of said toxicant by termites to at least ten percent abovethe rate of consumption of toxicant for an otherwise comparablecombination in the absence of said feeding stimulant.
 2. A combinationas recited in claim 1, wherein said toxicant, said feeding stimulant,and a consumable cellulosic material are admixed together.
 3. Acombination as recited in claim 1, wherein said toxicant and saidfeeding stimulant are not admixed together, whereby said feedingstimulant may be positioned in the vicinity of said toxicant.
 4. Acombination as recited in claim 1, additionally comprising at least onetermite attractant.
 5. A combination as recited in claim 4, wherein saidtermite attractant is selected from the group consisting of2-phenoxyethanol; naphthalene; δ-3-carene; 2,3,7-trimethyloctane;2,6,10-trimethyldodecane; elemene; α-longipinene; aristolene; calarene;β-guaiene; N-(1-methylhexylidene)-methylamine;2,6,10,14-tetramethylpentadecane; α-muurolene; and fenchone.
 6. Acombination as recited in claim 4, additionally comprising a perforatedtube holding said combination, wherein said perforated tube is adaptedfor insertion into the ground in the vicinity of a termite colony.
 7. Acombination as recited in claim 4, additionally comprising asemipermeable membrane holding said combination, wherein saidsemipermeable membrane is adapted for insertion into the ground in thevicinity of a termite colony.
 8. A combination as recited in claim 1,additionally comprising an effective amount of a second feedingstimulant comprising at least one free amino acid.
 9. A combination asrecited in claim 1, additionally comprising an effective amount of asecond feeding stimulant selected from the group consisting of asparticacid, glutamic acid, proline, ergosterol, and the fungus Gloeophyllumtrabeum.
 10. A method for killing termites, comprising the steps ofplacing near or in a termite colony a termite bait, and allowing thetermites to consume a sufficient amount of the bait to kill at leastsome of the termites in the colony; wherein the termite bait comprises atermite toxicant and an effective amount of a feeding stimulantcomprising at least one compound selected from the group consisting of2,6-di-t-butyl-4-methyl-phenol; naphthalene; ergosterol; hexanedioicacid dioctyl ester; and dioctyl phthalate; wherein an effective amountof the feeding stimulant is an amount that will increase the rate ofconsumption of the toxicant by termites to at least ten percent abovethe rate of consumption of toxicant for an otherwise comparable termitebait lacking the feeding stimulant.
 11. A method as recited in claim 10,wherein the termite bait comprises an admixture of the toxicant, thefeeding stimulant, and a consumable cellulosic material.
 12. A method asrecited in claim 10, wherein the toxicant and the feeding stimulant arenot admixed together, and wherein said placing step comprisespositioning the feeding stimulant in the vicinity of the toxicant.
 13. Amethod as recited in claim 10, additionally comprising the step ofplacing a termite attractant in the vicinity of the toxicant.
 14. Amethod as recited in claim 13, wherein the termite attractant isselected from the group consisting of 2-phenoxyethanol; naphthalene;δ-3-carene; 2,3,7-trimethyloctane; 2,6,10-trimethyldodecane; elemene;α-longipinene; aristolene; calarene; β-guaiene;N-(1-methylhexylidene)-methylamine; 2,6,10,14-tetramethylpentadecane;α-muurolene; and fenchone.
 15. A method as recited in claim 13, whereina perforated tube holding the toxicant, attractant, and stimulant isplaced in the vicinity of a termite colony.
 16. A method as recited inclaim 13, wherein a semipermeable membrane holding the toxicant,attractant, and stimulant is placed in the vicinity of a termite colony.17. A method as recited in claim 10, wherein the termite baitadditionally comprises an effective amount of a second feeding stimulantcomprising at least one free amino acid.
 18. A method as recited inclaim 10, additionally comprising an effective amount of a secondfeeding stimulant consisting of aspartic acid, glutamic acid, proline,ergosterol, and the fungus Gloeophyllum trabeum.
 19. A combination forkilling termites, comprising a termite toxicant and an effective amountof an attractant comprising at least one compound selected from thegroup consisting of 2-phenoxyethanol; naphthalene; δ-3-carene;2,3,7-trimethyloctane; 2,6,10-trimethyldodecane; elemene; α-longipinene;aristolene; calarene; β-guaiene; N(1-methylhexylidene)-methylamine;2,6,10,14-tetramethylpentadecane; α-muurolene; and fenchone; wherein aneffective amount of said attractant is an amount that will increase therate of consumption of said toxicant by termites to at least ten percentabove the rate of consumption of toxicant for an otherwise comparablecombination in the absence of said attractant.
 20. A combination asrecited in claim 19, wherein said toxicant, said attractant, and aconsumable cellulosic material are admixed together.
 21. A combinationas recited in claim 19, wherein said toxicant and said attractant arenot admixed together, whereby said attractant may be positioned in thevicinity of said toxicant.
 22. A combination as recited in claim 19,additionally comprising a perforated tube holding said combination,wherein said perforated tube is adapted for insertion into the ground inthe vicinity of a termite colony.
 23. A combination as recited in claim19, additionally comprising a semipermeable membrane holding saidcombination, wherein said semipermeable membrane is adapted forinsertion into the ground in the vicinity of a termite colony.
 24. Amethod for killing termites, comprising the steps of placing near or ina termite colony a termite bait, and allowing the termites to consume asufficient amount of the bait to kill at least some of the termites inthe colony; wherein the termite bait comprises a termite toxicant and aneffective amount of an attractant comprising at least one compoundselected from the group consisting of 2-phenoxyethanol; naphthalene;δ-3-carene; 2,3,7-trimethyloctane; 2,6,10-trimethyldodecane; elemene;α-longipinene; aristolene; calarene; β-guaiene;N-(1-methylhexylidene)-methylamine; 2,6,10,14-tetramethylpentadecane;α-muurolene; and fenchone; wherein an effective amount of the attractantis an amount that will increase the rate of consumption of the toxicantby termites to at least ten percent above the rate of consumption oftoxicant for an otherwise comparable termite bait in the absence of theattractant.
 25. A method as recited in claim 24, wherein the termitebait comprises an admixture of the toxicant the attractant, and aconsumable cellulosic material.
 26. A method as recited in claim 24,wherein the toxicant and the attractant are not admixed together, andwherein said placing step comprises positioning the attractant in thevicinity of the toxicant.
 27. A method as recited in claim 24, wherein aperforated tube holding the toxicant and attractant is inserted into theground in the vicinity of a termite colony.
 28. A method as recited inclaim 24, wherein a semipermeable membrane holding the toxicant andattractant is inserted into the ground in the vicinity of a termitecolony.